FIG. 1 is a top sectional view of a conventional projection apparatus 2, and includes a lamp unit 4 for producing light rays required for projecting an image. The lamp unit 4 includes a burner 404, a reflector 406 surrounding the burner 404, and a glass cover 402 disposed in front of the reflector 406. The reflector 406 and the glass cover 402 cooperatively define an air inlet 5a at one side of the reflector 406 and an air outlet 5b at the other side of the reflector 406.
In order to reduce the intensive heat generated during use, an axial fan unit 6 is usually provided at one side of the reflector 406, thereby lowering the temperature at an outer side of the reflector 406. A blower 8 is further provided for generating airflow within the conventional projection apparatus 2, and is connected to the lamp unit 4 by a guiding duct 7 so as to guide the air to flow into the reflector 406 to disperse heat of the burner 404 via the air inlet 5a and flow out of the lamp unit 4 via the air outlet 5b. In this way, the temperature of the burner 404 within the reflector 406 is reduced considerably.
Implementation of the fan unit 6 and the blower 8 reduces the receiving space and consequently hinder the object of producing the conventional projection apparatus in compact size.
Moreover, the lamp unit 4 may explode or burnout due to the intensive heat. In case of lamp explosion, tiny broken pieces within the reflector 406 may scatter over the projection apparatus 2 via the air inlet 5a and outlet 5b, thereby injuring a user when the user cleans the broken pieces. It is relatively difficult to clean the tiny broken pieces scattered over the projection apparatus 2.